Systems and methods for forming a desired bend angle in an orthodontic appliance

ABSTRACT

A method for forming a desired bend angle in an orthodontic appliance comprising: monitoring bending of the orthodontic appliance in a gripped state, the monitoring being continuous; in response to an initial bend angle in the orthodontic appliance in the gripped state being reached, causing the release of at least a portion of the orthodontic appliance so that orthodontic appliance is in a free state, measuring resultant angle of the bend in the free state; in response to resultant angle being within a predefined tolerance of the desired bend angle, determining that desired bend angle has been reached.

CROSS-REFERENCE

The present application is a continuation application of U.S. patentapplication Ser. No. 16/014,253, filed Jun. 21, 2018, the entirety ofwhich is incorporated herein by reference.

FIELD

The present technology relates to systems and methods for forming adesired bend in an orthodontic appliance.

BACKGROUND

In orthodontics, treatments for achieving alignment of malposed teeth ina patient include applying orthodontic appliances to the patient'steeth, such as pre-shaped orthodontic wire attached to the bracketswhich are themselves attached to the teeth. The wires are typically madefrom shape memory alloys which have the ability to recover their shapeafter being deformed. This re-shaping occurs at a predeterminedtemperature, usually around 38° C. Shape memory alloys used inorthodontic archwires include nickel-titanium alloys (e.g. Nitinol™),beta-titanium alloys, and copper nickel-titanium alloys.

The wires are typically pre-shaped into a desired shape by forming bendsat desired positions and with desired angles, heating under tension, andsuper-cooling. The heating step typically comprises electric heating.Once pre-shaped, the wire is attached to the brackets by bending itsshape to conform to the general shape of the malposed teeth. When thewire warms to mouth temperature it reverts to its original shape therebyexerting a force on the teeth to which it is attached to move them.

At least the bending portion of the pre-shaping process can be achievedmanually or using bending apparatus such as those described in U.S. Pat.Nos. 6,612,143, 6,732,558, 6,755,064, 6,860,132, 7,076,980, 7,283,891and US2010275668.

In certain pre-shaping methods, the desired bend in the orthodonticappliance is achieved by iteratively bending the orthodontic appliance,and assessing the acquired bend until the desired bend is achieved. Thiscan take many iterations which has associated inconveniences of materialproperty degradation in the orthodontic appliance, as well as increasedtime and cost per orthodontic appliance manufacture.

U.S. Pat. No. 6,612,143 describes a robotic bending apparatus forbending archwires and other types of elongate, bendable medical devicesinto a desired configuration and includes a first gripping tool and amoveable gripping tool. The first gripping tool can be either fixed withrespect to a base or table for the robot or positioned at the end ofrobot arm. The moveable gripping tool is mounted to the end of amoveable robot arm having a proximal portion also mounted to the base.The robot preferably comprises a six axis bending robot, in which thedistal end of the moveable arm can move relative to the fixed grippingtool about three translational axes and three rotational axes. Thegripping tools preferably incorporate force sensors which are used todetermine overbends needed to get the desired final shape of thearchwire. The robot may also include a resistive heating system in whichcurrent flows through the wire while the wire is held in a bentcondition to heat the wire and thereby retain the bent shape of thewire. A magazine for holding a plurality of straight archwires needingto be bent and a conveyor system for receiving the wires after thebending process is complete are also described. The robot bending systemis able to form archwires with any required second and third order bendsquickly and with high precision. As such, it is highly suitable for usein a precision appliance-manufacturing center manufacturing a largenumber of archwires (or other medical devices or appliances) for adistributed base of clinics.

U.S. Pat. No. 9,901,705 describes an apparatus, system, and method forcreating a curvature on a medical device during a medical procedure, forexample, selecting a curvature from a curve database, customizing thecurvature for a specific patient anatomy, and applying the curvature tothe medical device during the medical procedure.

It is an object of the present technology to ameliorate at least some ofthe inconveniences present in the prior art.

SUMMARY

Embodiments of the present technology have been developed based ondevelopers' appreciation of certain shortcomings associated with theexisting systems for forming a desired bend in orthodontic appliances.

In particular, developers have noted a difficulty with accurately andreproducibly achieving the desired bend in the orthodontic applianceduring the pre-shaping. The process of pre-shaping the archwires intothe desired shape is also referred to in the art as “shape forming” or“shape setting”. It has been noted that orthodontic appliance materials,such as wires made of shape memory alloys, have a spring-back effectwhen released from its grip during bend formation. This requires acompensation in the form of an over-bend applied to the wire duringbending. In other words, the wire must be bent further than the requiredangle of the desired bend. This problem is confounded by the fact thatthe required over-bend varies from orthodontic appliance to orthodonticappliance, most likely due to differences in elastic properties from theshape memory alloy composition, manufacturing method and archwiredimensions. These manufacturing tolerances may exist within and betweenbatches of the orthodontic appliance blanks as produced. Consider alsothat each orthodontic appliance blank that is provided for pre-shapinghas itself undergone a number of prior processing steps each with itsown manufacturing tolerances (composition, casting, shaping).Furthermore, the ability to assess whether the desired bend has beenachieved is highly dependent on: (i) operator skill and judgement, ifperformed manually, (ii) calibration of bending apparatus and bendassessment apparatus, if performed automatically or semi-automatically.

One consequence of multiple attempts to achieve the desired bend in theorthodontic appliance is a degradation in certain material properties,and ultimately failure of the material through material fatigue. Anotherconsequence is an increased time, and hence cost, to manufacture eachorthodontic appliance. Consequences to the patient of applying anorthodontic appliance with an incorrect pre-form bend is incorrectalignment of their teeth with possible impact on jaw alignment andassociated medical problems, increased discomfort, and longer treatment,resulting in a higher cost.

Broadly, developers have determined a method and a system of forming adesired bend angle, by determining an initial angle determined by atrained Machine Learning Algorithm (MLA), and a feedback loop based on acomputer vision analysis of a resultant bend angle after applying theinitial angle.

From one aspect, there is provided a method for forming a desired bendangle in an orthodontic appliance, the method being implemented by aprocessor of a computer system, the computer system operatively coupledto a bending apparatus, the method comprising:—monitoring bending of theorthodontic appliance in a gripped state through a computer visionanalysis, the monitoring being a continuous monitoring of the bending ofthe orthodontic appliance in the gripped state throughout an entirebending process; in response to the computer vision analysis renderingan indication that an initial bend angle in the orthodontic appliance ina gripped state having been reached, causing the bending apparatus torelease at least a portion of the orthodontic appliance so that theorthodontic appliance is in a free state, the initial bend angle havingbeen determined by a Machine Learning Algorithm (MLA); measuring aresultant angle of the bend through the computer vision analysis, whenthe orthodontic appliance is in the free state; in response to theresultant angle being within a predefined tolerance level of the desiredbend angle, determining that the orthodontic appliance has reached thedesired bend angle.

In certain embodiments, the method further comprises in response to theresultant angle being outside the predefined tolerance level of thedesired bend angle, iteratively applying an adjusted bend angle to theorthodontic appliance in the gripped state until the desired bend angleis achieved as determined by the computer vision analysis in the freestate.

In certain embodiments, the computer system executes the MLA fordetermining the initial bend angle to be applied to the orthodonticappliance during bending in the gripped state of the orthodonticappliance for achieving the desired bend angle in the orthodonticappliance when the orthodontic appliance is in the free state.

In certain embodiments, the obtaining the indication of the desired bendangle in the orthodontic appliance comprises receiving the indicationfrom an operator of the computer system.

In certain embodiments, the obtaining the indication of the desired bendangle in the orthodontic appliance comprises calculating, by thecomputer system, the desired bend angle.

In certain embodiments, the method further comprises, prior to theobtaining the indication of the desired bend angle: executing a trainingprocess for the MLA.

In certain embodiments, the training process includes providing afeedback loop based on the computer vision analysis.

In certain embodiments, in response to the resultant angle being outsidethe predefined tolerance level of the desired bend angle, iterativelyapplying an adjusted bend angle to the orthodontic appliance in thegripped state until the desired bend angle is achieved as determined bythe computer vision analysis in the free state, the method furthercomprising feeding the adjusted bend angle to the MLA to be used forfurther retraining of the MLA.

In certain embodiments, the training process comprises providing atleast one training set, the training set including an indication of aproperty of the orthodontic appliance and a target value representativeof a desired bend; the property of the orthodontic appliance includingat least one of: an elasticity property of a material from which theorthodontic appliance is formed, a thickness of the orthodonticappliance, a diameter of the orthodontic appliance, a composition of thematerial from which the orthodontic appliance is formed, and amanufacturing process of the orthodontic appliance.

In certain embodiments, the training process further comprises:executing a test bending to bend a test orthodontic appliance to thedesired bend; calculating a variance parameter between an actual bendand the desired bend; feeding back the variance parameter to the MLA forfurther retraining of the MLA.

In certain embodiments, the method further comprises iterativelyexecuting the training process until the variance parameter is within apre-determined acceptable error threshold.

In certain embodiments, the monitoring of the bending of the orthodonticappliance comprises: capturing a sequence of images of the bend as it isbeing formed during the bending; filtering the images to determine acontour of the orthodontic appliance; determining at least one elongateaxis of the orthodontic appliance from the contour; and determining anangle between the at least one elongate axis of the orthodonticappliance and a reference axis, or between two elongate axes of theorthodontic appliance.

In certain embodiments, the reference axis is determined by projecting avirtual axis onto, and aligned with, the image of the orthodonticappliance before causing the bending apparatus to form the bend in theorthodontic appliance.

In certain embodiments, the filtering comprises one or more of imagescaling, adjusting focus, and cancelling image noise, the filteredimages being of HSV image format.

From another aspect, there is provided a system for forming a desiredbend angle in an orthodontic appliance, the system comprising: a bendingapparatus operatively coupled to a computer system; the computer systemhaving a processor arranged to execute a method, the method comprising:monitoring bending of the orthodontic appliance in a gripped statethrough a computer vision analysis, the monitoring being a continuousmonitoring of the bending of the orthodontic appliance in the grippedstate throughout an entire bending process; in response to the computervision analysis rendering an indication that an initial bend angle inthe orthodontic appliance in a gripped state having been reached,causing the bending apparatus to release at least a portion of theorthodontic appliance so that the orthodontic appliance is in a freestate, the initial bend angle having been determined by a MachineLearning Algorithm (MLA); measuring a resultant angle of the bendthrough the computer vision analysis, when the orthodontic appliance isin the free state; and in response to the resultant angle being within apredefined tolerance level of the desired bend angle, determining thatthe orthodontic appliance has reached the desired bend angle.

In certain embodiments, the system further comprises a computer visionsystem arranged to perform at least a portion of the computer visionanalysis, the computer system and the computer vision system beingoperatively connected thereto.

From a further aspect there is provided a method for monitoring aformation of a bend in an orthodontic appliance, the method beingimplemented by a processor of a computer system operatively connected toa computer vision system, the method comprising: obtaining a sequence ofimage frames of the orthodontic appliance during a bending process, theorthodontic appliance having a first bend arm and a second bend arm; forat least one of the image frames of the sequence of image frames:applying image processing steps to objects in the image frames to detectat least a portion of the first bend arm and at least a portion of thesecond bend arm; deriving one or more of: an elongate axis of the firstbend arm based on the detected at least portion of the first bend arm,and an elongate axis of the second bend arm based on the detected atleast portion of the second bend arm; determining a bend angle of theorthodontic appliance based on: the elongate axis of the first bend armand the elongate axis of the second bend arm, or the elongate axis ofthe first bend arm or the second bend arm, and a reference axis.

In certain embodiments, the bend angle of the orthodontic appliance ismonitored continuously during the bend process.

In certain embodiments, the reference axis is determined by projecting avirtual axis onto, and aligned with, the image of the orthodonticappliance before causing the bending apparatus to form the bend in theorthodontic appliance.

In certain embodiments, further comprising maintaining the alignment ofthe virtual axis on an image of at least a portion of the orthodonticappliance during the bending process.

From another aspect, there is provided a method for forming a desiredbend angle in an orthodontic appliance, the method being implemented bya processor of a computer system, the computer system executing aMachine Learning Algorithm, the computer system operatively coupled to abending apparatus, the method comprising obtaining an indication of thedesired bend angle in the orthodontic appliance; determining, by theMLA, an initial bend angle to be applied to the orthodontic applianceduring bending in a gripped state of the orthodontic appliance forachieving the desired bend angle in the orthodontic appliance when theorthodontic appliance is in a free state; causing the bending apparatusto form a bend having the initial bend angle in the orthodonticappliance, by bending the orthodontic appliance in the gripped state;monitoring the bending of the orthodontic appliance in the gripped statethrough a computer vision analysis; in response to the computer visionanalysis rendering an indication that the initial bend angle in theorthodontic appliance in the gripped state has been reached, causing thebending apparatus to release at least a portion of the orthodonticappliance so that the orthodontic appliance is in the free state,measuring a resultant angle of the bend through the computer visionanalysis, when the orthodontic appliance is in the free state;selectively executing: in response to the resultant angle being within apredefined tolerance level of the desired bend angle, determining thatthe orthodontic appliance has reached the desired bend angle; and inresponse to the resultant angle being outside the predefined tolerancelevel of the desired bend angle, iteratively applying an adjusted bendangle to the orthodontic appliance in the gripped state until thedesired bend angle is achieved as determined by the computer visionanalysis in the free state. The method may further comprise feeding theadjusted bend angle to the MLA to be used for further retraining of theMLA.

In certain embodiments, the obtaining the indication of the desired bendangle in the orthodontic appliance comprises receiving the indicationfrom an operator of the computer system. In certain embodiments, theobtaining the indication of the desired bend angle in the orthodonticappliance comprises calculating, by the computer system, the desiredbend angle.

In certain embodiments, the method further comprises, prior to theobtaining the indication of the desired bend angle: executing a trainingprocess for the MLA. The training process may include providing afeedback loop based on the computer vision analysis.

In certain embodiments, the training process comprises providing atleast one training set, the training set including an indication of aproperty of the orthodontic appliance and a target value representativeof a desired bend; the property of the orthodontic appliance includingat least one of: an elasticity property of a material from which theorthodontic appliance is formed, a thickness of the orthodonticappliance, a diameter of the orthodontic appliance, a composition of thematerial from which the orthodontic appliance is formed, and amanufacturing process of the orthodontic appliance.

In certain embodiments, the training process further comprises:executing a test bending to bend a test orthodontic appliance to thedesired bend; calculating a variance parameter between an actual bendand the desired bend; and feeding back the variance parameter to the MLAfor further retraining of the MLA.

In certain embodiments, the method further comprises iterativelyexecuting the training process until the variance parameter is within apre-determined acceptable error threshold.

In certain embodiments, the monitoring of the bending of the orthodonticappliance comprises: capturing a sequence of images of the bend as it isbeing formed during the bending; filtering the images to determine acontour of the orthodontic appliance; determining at least one elongateaxis of the orthodontic appliance from the contour; and determining anangle between the at least one elongate axis of the orthodonticappliance and a reference axis, or between two elongate axes of theorthodontic appliance. In certain embodiments, two elongate(longitudinal) axes of the orthodontic appliance are derived from thecontour; and an angle between the two longitudinal axes of theorthodontic appliance is determined.

In certain embodiments, the reference axis is determined by projecting avirtual axis onto, and aligned with, the image of the orthodonticappliance before causing the bending apparatus to form the bend in theorthodontic appliance. In certain embodiments, the alignment of thevirtual axis is maintained on an image of at least a portion of theorthodontic appliance during the bending process.

In certain embodiments, the filtering comprises one or more of imagescaling, adjusting focus, and cancelling image noise. The filtering mayfurther comprise transforming the format of the filtered images. In oneembodiment, the format of the filtered images is transformed to HSV.

In certain embodiments, the monitoring of the bending of the orthodonticappliance comprises determining an angle of the bend being formedrelative to a starting position or reference axis, the starting positioncomprising a virtual axis projected onto and aligned with the image ofthe orthodontic appliance before causing the bending apparatus to formthe bend in the orthodontic appliance. The virtual axis can be areference point. The virtual axis may be aligned with an elongate axisof the orthodontic appliance.

In certain embodiments, the monitoring the bending of the orthodonticappliance in the gripped state through the computer vision analysiscomprises continuously monitoring the bending of the orthodonticappliance in the gripped state throughout an entire bending process. Incertain embodiments, the monitoring the bending of the orthodonticappliance in the gripped state through the computer vision analysiscomprises monitoring a bend angle of the orthodontic appliance in thegripped state throughout an entire bending process. In certainembodiments, the monitoring the bending of the orthodontic appliance inthe gripped state through the computer vision analysis comprisesacquiring a plurality of sequential image frames of the orthodonticappliance during the bending process at a frame acquisition rate relatedto a rate of bending. In certain embodiments, the frame acquisition rateis equal to or higher than about 70 frames per second, about 80 framesper second, about 90 frames per second, about 100 frames per second,about 150 frames per second, about 200 frames per second, about 250frames per second, or about 300 frames per second. In certainembodiments, the frame acquisition rate is between about 70 to about 300frames per second, about 100 to about 250 frames per second, or about150 to about 200 frames per second.

From another aspect, there is provided a system for forming a desiredbend angle in an orthodontic appliance, the system comprising a bendingapparatus operatively coupled to a computer system; the computer systemexecuting a Machine Learning Algorithm (MLA) and having a processorarranged to execute a method. The method comprises obtaining anindication of the desired bend angle in the orthodontic appliance;determining, by the MLA, an initial bend angle to be applied to theorthodontic appliance during bending in a gripped state of theorthodontic appliance for achieving the desired bend angle in theorthodontic appliance when the orthodontic appliance is in a free state;causing the bending apparatus to form a bend having the initial bendangle in the orthodontic appliance, by bending the orthodontic appliancein the gripped state; monitoring the bending of the orthodonticappliance in the gripped state through a computer vision analysis; inresponse to the computer vision analysis providing an indication thatthe initial bend angle in the orthodontic appliance in the gripped statehas been reached, causing the bending apparatus to release at least aportion of the orthodontic appliance so that the orthodontic applianceis in the free state; measuring a resultant angle of the bend throughthe computer vision analysis, when the orthodontic appliance is in thefree state; selectively executing: in response to the resultant anglebeing within a predefined tolerance level of the desired bend angle,determining that the orthodontic appliance has reached the desired bendangle; and in response to the resultant angle being outside thepredefined tolerance level of the desired bend angle, iterativelyapplying an adjusted bend angle to the orthodontic appliance in thegripped state until the desired bend angle is achieved as determined bythe computer vision analysis in the free state.

In certain embodiments, the system further comprises a computer visionsystem arranged to perform at least a portion of the computer visionanalysis, the computer system and the computer vision system beingoperatively connected thereto.

From another aspect, there is provided a method for training a MachineLearning Algorithm (MLA), the MLA for determining, in use, a bend angleto be applied to an orthodontic appliance during bending in a grippedstate for achieving a desired bend angle in the orthodontic appliancewhen in a free state, the method being implemented by a processor of acomputer system, the computer system operatively coupled to a bendingapparatus. The method comprises obtaining an indication of the desiredbend angle in the orthodontic appliance; causing the bending apparatusto form a bend having an initial bend angle in the orthodonticappliance, by bending the orthodontic appliance in the gripped state; inresponse to receiving an indication that the initial bend angle in theorthodontic appliance in the gripped state has been reached, causing thebending apparatus to release at least a portion of the orthodonticappliance so that the orthodontic appliance is in the free state;obtaining a measure of a resultant angle of the bend, when theorthodontic appliance is in the free state; generating a training setfor training the MLA, the training set including: an indication of aproperty of the orthodontic appliance and a target value representativeof a desired bend; the property of the orthodontic appliance includingat least one of: an elasticity property of a material from which theorthodontic appliance is formed, a thickness of the orthodonticappliance, a diameter of the orthodontic appliance, a composition of theorthodontic appliance, and a manufacturing method of the orthodonticappliance; the target value comprises the initial bend angle; andwherein the training set is configured to train the MLA to predict theinitial bend angle based on the desired bend angle and the property ofthe orthodontic appliance.

In certain embodiments, the method further comprises calculating adifference parameter between the resultant angle of the bend and theinitial bend angle and feeding the difference parameter as an indicationof the prediction error.

In certain embodiments, the method further comprises iterativelyrepeating the method for training until the prediction error is within apre-determined threshold.

In certain embodiments, the obtaining the measure of the resultant angleof the bend, when the orthodontic appliance is in the free state,comprises applying an optical feedback analysis. In certain embodiments,the obtaining the measure of the resultant angle of the bend can beperformed in any other way, such as by force sensors and the like.

In certain embodiments, the optical feedback analysis comprisesmonitoring the bending of the orthodontic appliance in the gripped statethrough a computer vision analysis to determine when the initial bendangle in the orthodontic appliance in the gripped state has beenreached; and measuring a resultant angle of the bend through thecomputer vision analysis, when the orthodontic appliance is in the freestate; selectively executing: in response to the resultant angle beingwithin a predefined tolerance level of the desired bend angle,determining that the orthodontic appliance has reached the desired bendangle; and in response to the resultant angle being outside thepredefined tolerance level of the desired bend angle, iterativelyapplying an adjusted bend angle to the orthodontic appliance in thegripped state until the desired bend angle is achieved as determined bythe computer vision analysis in the free state.

From another aspect, there is provided a system for training a MachineLearning Algorithm (MLA), the MLA for determining, in use, a bend angleto be applied to an orthodontic appliance during bending in a grippedstate for achieving a desired bend angle in the orthodontic appliancewhen in a free state, the system comprising a computer systemoperatively coupled to a bending apparatus, the computer system having aprocessor arranged to execute a method. The method comprises: obtainingan indication of the desired bend angle in the orthodontic appliance;causing the bending apparatus to form a bend having an initial bendangle in the orthodontic appliance, by bending the orthodontic appliancein the gripped state; in response to receiving an indication that theinitial bend angle in the orthodontic appliance in the gripped state hasbeen reached, causing the bending apparatus to release at least aportion of the orthodontic appliance so that the orthodontic applianceis in the free state; obtaining a measure of a resultant angle of thebend, when the orthodontic appliance is in the free state; generating atraining set for training the MLA, the training set including: anindication of a property of the orthodontic appliance and a target valuerepresentative of a desired bend, the property of the orthodonticappliance including at least one of: an elasticity property of amaterial from which the orthodontic appliance is formed, a thickness ofthe orthodontic appliance, a diameter of the orthodontic appliance, acomposition of the orthodontic appliance, and a manufacturing method ofthe orthodontic appliance; the target value comprises the initial bendangle; and wherein the training set is configured to train the MLA topredict the initial bend angle based on the desired bend angle and theproperty of the orthodontic appliance.

In certain embodiments, any one or more of the method steps of (i)determining an initial bend angle to be applied, (ii) causing thebending apparatus to form a bend, (iii) monitoring the bending, (iv)rendering an indication that the initial bend angle has been reached,(v) measuring a resultant angle, (vi) determining that the resultantangle is within a predefined tolerance, (vii) determining that theresultant angle is not within a predefined tolerance and applying anadjusted angle, are performed in real-time. In certain embodiments, anyone or more of these method steps are performed automatically withoutuser intervention.

In certain embodiments, any one or more of the method steps of (i)determining an initial bend angle to be applied, (ii) causing thebending apparatus to form a bend, (iii) monitoring the bending, (iv)obtaining a measure of a resultant angle, and (v) generating a trainingset, are performed in real-time. In certain embodiments, any one or moreof these method steps are performed automatically without userintervention.

In certain embodiments, the desired bend is achieved in the orthodonticappliance in fewer iterations compared with systems of the prior art. Incertain embodiments, the desired bend is achieved in the orthodonticappliance faster compared with systems of the prior art.

In certain embodiments, the initial bend, provided by the MLA, angle canbe achieved in a single step. This can reduce the number of iterationsrequired to achieve the desired bend.

From another aspect, there is provided a method for monitoring aformation of a bend in an orthodontic appliance, the method beingimplemented by a processor of a computer system operatively connected toa computer vision system, the method comprising:

capturing a sequence of image frames of the orthodontic appliance duringa bending process, the orthodontic appliance having a first bend arm anda second bend arm;

for at least one of the image frames of the sequence of image frames:

-   -   applying image processing steps to objects in the image frames        to determine a contour of the imaged orthodontic appliance        including a contour of at least a portion of the first bend arm        and a contour of at least a portion of the second bend arm;    -   deriving one or more of: an elongate axis of the first bend arm        based on the contour of the first bend arm, and an elongate axis        of the second bend arm based on the contour of the second bend        arm;    -   determining a bend angle of the orthodontic appliance based on:        -   the elongate axis of the first bend arm and the elongate            axis of the second bend arm, or        -   the elongate axis of the first bend arm or the second bend            arm, and a reference axis;            wherein the bend angle of the orthodontic appliance is            monitored continuously during the bend process.

In certain embodiments, the sequence of image frames is captured at anacquisition rate of about 70 to about 300 frames per second.

In certain embodiments, the image frames have a magnification of about50× to about 400×.

In certain embodiments, the computer vision system further comprises abackground surface against which the orthodontic appliance is imaged,wherein the background surface comprises one or more of a chroma-keysurface and a light-absorbing surface.

In certain embodiments, the reference axis is determined by projecting avirtual axis onto, and aligned with, the image of the orthodonticappliance before causing the bending apparatus to form the bend in theorthodontic appliance.

In certain embodiments, the method further comprises maintaining thealignment of the virtual axis on an image of at least a portion of theorthodontic appliance during the bending process.

In the context of the present specification, unless expressly providedotherwise, a computer system may refer, but is not limited to, an“electronic device”, an “operation system”, a “system”, a“computer-based system”, a “controller unit”, a “control device” and/orany combination thereof appropriate to the relevant task at hand.

In the context of the present specification, unless expressly providedotherwise, the expression “computer-readable medium” and “memory” areintended to include media of any nature and kind whatsoever,non-limiting examples of which include RAM, ROM, disks (CD-ROMs, DVDs,floppy disks, hard disk drives, etc.), USB keys, flash memory cards,solid state-drives, and tape drives.

In the context of the present specification, a “database” is anystructured collection of data, irrespective of its particular structure,the database management software, or the computer hardware on which thedata is stored, implemented or otherwise rendered available for use. Adatabase may reside on the same hardware as the process that stores ormakes use of the information stored in the database or it may reside onseparate hardware, such as a dedicated server or plurality of servers.

In the context of the present specification, unless expressly providedotherwise, the words “first”, “second”, “third”, etc. have been used asadjectives only for the purpose of allowing for distinction between thenouns that they modify from one another, and not for the purpose ofdescribing any particular relationship between those nouns.

Implementations of the present technology each have at least one of theabove-mentioned object and/or aspects, but do not necessarily have allof them. It should be understood that some aspects of the presenttechnology that have resulted from attempting to attain theabove-mentioned object may not satisfy this object and/or may satisfyother objects not specifically recited herein.

Additional and/or alternative features, aspects and advantages ofimplementations of the present technology will become apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present technology, as well as otheraspects and further features thereof, reference is made to the followingdescription which is to be used in conjunction with the accompanyingdrawings, where:

FIG. 1 is a schematic diagram of an orthodontic appliance attached toteeth with brackets, to which certain embodiments of the methods andsystems of the present technology can be applied;

FIG. 2 is the orthodontic appliance of FIG. 1 showing bends formed inthe orthodontic appliance according to certain embodiments of themethods and systems of the present technology;

FIG. 3 is the orthodontic appliance of FIG. 2 showing differentpositions of the orthodontic appliance during formation of one of thebends according to certain embodiments of the methods and systems of thepresent technology;

FIG. 4 is a system for forming bends in the orthodontic appliance, thesystem comprising a computer system and a bending apparatus, accordingto certain embodiments of the present technology;

FIG. 5 is a system for forming bends in the orthodontic appliance, thesystem comprising a computer system, a bending apparatus and a computervision system, according to certain embodiments of the presenttechnology;

FIG. 6 is one embodiment of a computing environment of the computersystem of FIG. 4 or FIG. 5 according to certain embodiments of themethods and systems of the present technology;

FIG. 7 is a schematic diagram of one embodiment of the bending apparatusof the system of FIG. 4 or FIG. 5 according to certain embodiments ofmethods and systems of the present technology;

FIG. 8 is a schematic diagram of one embodiment of the computer visionsystem of the system of FIG. 4 or FIG. 5 according to certainembodiments of methods and systems of the present technology;

FIG. 9 is an example of an image of the orthodontic appliance capturedby the computer vision system of FIG. 8 before image processing;

FIG. 10 is the image of the orthodontic appliance of FIG. 9 after imageprocessing;

FIG. 11 is a diagram of a method for forming bends in the orthodonticappliance executed by the computer system of FIG. 4 or FIG. 5, inaccordance with certain embodiments of the present technology; and

FIG. 12 is a diagram of a method for training a Machine LearningAlgorithm executed by the computer system of FIG. 4 or FIG. 5, inaccordance with certain embodiments of the present technology.

It should be noted that, unless otherwise explicitly specified herein,the drawings are not to scale.

DETAILED DESCRIPTION

Certain aspects and embodiments of the present technology, are directedto methods and systems for forming a desired bend in an orthodonticappliance. Other aspects and embodiments of the present technology aredirected to training a Machine Learning Algorithm (MLA) for determining,in use, a bend angle to be applied to an orthodontic appliance duringbending in a gripped state for achieving a desired bend angle in theorthodontic appliance when in a free state. By “gripped state” is meantthat the orthodontic appliance is restrained in the ability to movefreely, such as during bending of the orthodontic appliance when theorthodontic appliance is gripped on either side of the bend. By “freestate” is meant that the orthodontic appliance is not restrained in theability to move freely, such as when at least one end of the orthodonticappliance is released.

Referring initially to FIG. 1, there is shown an orthodontic appliance10 to which aspects and embodiments of the present technology can beapplied. In this embodiment, the orthodontic appliance 10 is an archwire10 made of a shape memory alloy. The shape memory alloy is Nitonol™, butcan also be any other shape memory alloy or material with elasticproperties. Brackets 20 are provided on each tooth 30 a, 30 b, 30 c, 30d, 30 e, and the archwire 10 extends between, and is connected to, eachof the brackets 20. As illustrated, the maloclusion is misalignment ofthe tooth 30 c for which the treatment plan as illustrated is an upwardmovement to align the tooth 30 c with neighbouring the teeth 30 a, 30 b,30 d, 30 e.

As can be seen, the archwire 10 of FIG. 1 has three bends A, B and Cwith bend angles θ_(A), θ_(B) and θ_(c) respectively, shown in FIG. 2.FIG. 3 shows bend A of FIG. 2, including a starting position 40, adesired position 50 with the desired bend angle θ_(A), and an overbendposition 60 having an overbend angle θ_(AOB) which must be appliedduring bend formation in order to achieve the desired bend angle θ_(B)due to an elastic property of the archwire 10.

It will be appreciated that in other embodiments, systems and methods ofthe present technology can be applied to different types, shapes, sizesand configurations of orthodontic appliances such as multi-strand wires,strips or retainers to adjust their configuration. Furthermore, theformed bends may comprise rounded corners or even loops. It will also beappreciated that the orthodontic appliance may be used for treating anytype of teeth misalignment or maloclusion, including but not limited toclosing gaps (“space closure”), creating/widening gaps, tooth rotation,tooth intrusion/extrusion, and translation, to name a few.

Referring now to FIG. 4, there is shown one embodiment of a system 100suitable for implementing non-limiting embodiments of the presenttechnology. The system 100 will be described with reference to formingthe desired bend angle θ_(A) in the bend A of the orthodontic appliance10 of FIGS. 1-3.

It is to be expressly understood that the system 100 as depicted ismerely an illustrative implementation of the present technology. Thus,the description thereof that follows is intended to be only adescription of illustrative examples of the present technology. Thisdescription is not intended to define the scope or set forth the boundsof the present technology. In some cases, what are believed to behelpful examples of modifications to the system 100 may also be setforth below. This is done merely as an aid to understanding, and, again,not to define the scope or set forth the bounds of the presenttechnology. These modifications are not an exhaustive list, and, as aperson skilled in the art would understand, other modifications arelikely possible. Further, where this has not been done (i.e., where noexamples of modifications have been set forth), it should not beinterpreted that no modifications are possible and/or that what isdescribed is the sole manner of implementing that element of the presenttechnology. As a person skilled in the art would understand, this islikely not the case. In addition it is to be understood that the system100 may provide in certain instances simple implementations of thepresent technology, and that where such is the case they have beenpresented in this manner as an aid to understanding. As persons skilledin the art would understand, various implementations of the presenttechnology may be of a greater complexity.

The system 100 of FIG. 4 comprises a computer system 110 operativelycoupled to a bending apparatus 120. Broadly, responsive to instructionsfrom the computer system 110, the bending apparatus 120 is configured toform a bend in the archwire 10 having an initial bend angle asdetermined in the gripped state. The bending apparatus is also arrangedto grip or release the archwire 10 in order to allow transition betweenthe gripped and free states. In these embodiments, monitoring of thebend of the archwire 10 and determination of the initial bend angle inthe gripped state and a resultant bend angle in the free state can beperformed by any means and this information provided to the computersystem 110. The computer system 110 can, selectively execute, inresponse to the resultant angle being within a predefined tolerancelevel of an obtained desired bend angle (e.g. θ_(A)) in the free state,determine that the archwire 10 has reached the desired bend angle; andin response to the resultant angle being outside the predefinedtolerance level of the desired bend angle in the free state, iterativelyapply an adjusted bend angle to the archwire 10 in the gripped stateuntil the desired bend angle in the free state is achieved. Certainembodiments of the bending apparatus 120 will be described later withreference to FIG. 7.

FIG. 5 illustrates another embodiment of the system 100 of FIG. 4, inwhich there is further provided a computer vision system 130 forproviding a computer vision analysis of the bend. The computer visionsystem 130 is operatively connected to the computer system 110, andoptionally connected to the bending apparatus 120. In certainembodiments, the computer vision system 130 is configured to monitor thebending of the archwire 10 in the gripped state for determining that theinitial bend angle in the archwire 10 in the gripped state has beenreached, and for measuring a resultant angle of the bend when theorthodontic appliance is in the free state. In certain embodiments, thecomputer vision system 130 is configured to continuously monitor thebending of the archwire 10 through an entire bending process. Certainembodiments of the computer vision system 130 and the computer visionanalysis will be described later with reference to FIG. 8.

Turning first to the computer system 110, certain embodiments of thecomputer system 110 have a computer environment 140 as illustratedschematically in FIG. 6 and comprises various hardware componentsincluding one or more single or multi-core processors collectivelyrepresented by a processor 150, a solid-state drive 160, a random accessmemory 170 and an input/output interface 180. Communication between thevarious components of the computing environment 140 may be enabled byone or more internal and/or external buses 190 (e.g. a PCI bus,universal serial bus, IEEE 1394 “Firewire” bus, SCSI bus, Serial-ATAbus, ARINC bus, etc.), to which the various hardware components areelectronically coupled.

The input/output interface 180 allows enabling networking capabilitiessuch as wire or wireless access. As an example, the input/outputinterface 180 comprises a networking interface such as, but not limitedto, a network port, a network socket, a network interface controller andthe like. Multiple examples of how the networking interface may beimplemented will become apparent to the person skilled in the art of thepresent technology. For example, but without being limiting, thenetworking interface 180 may implement specific physical layer and datalink layer standard such as Ethernet, Fibre Channel, Wi-Fi or TokenRing. The specific physical layer and the data link layer may provide abase for a full network protocol stack, allowing communication amongsmall groups of computers on the same local area network (LAN) andlarge-scale network communications through routable protocols, such asInternet Protocol (IP).

According to implementations of the present technology, the solid-statedrive 160 stores program instructions suitable for being loaded into therandom access memory 170 and executed by the processor 150 for executingmethods according to certain aspects and embodiments of the presenttechnology. For example, the program instructions may be part of alibrary or an application.

In this embodiment, the computing environment 140 is implemented in ageneric computer system which is a conventional computer (i.e. an “offthe shelf” generic computer system). The generic computer system is adesktop computer/personal computer, but may also be any other type ofelectronic device such as, but not limited to, a laptop, a mobiledevice, a smart phone, a tablet device, or a server.

In other embodiments, the computing environment 140 is implemented in adevice specifically dedicated to the implementation of the presenttechnology. For example, the computing environment 140 is implemented inan electronic device such as, but not limited to, a desktopcomputer/personal computer, a laptop, a mobile device, a smart phone, atablet device, a server, specifically designed for forming the desiredbend angle in an orthodontic appliance. The electronic device may alsobe dedicated to operating other devices, such as the bending apparatus120 and/or the computer vision system 130.

In some embodiments, the computing environment 140 is distributedamongst multiple systems, such as the bending apparatus 120, thecomputer vision system 130, and/or a server. In some embodiments, thecomputing environment 140 may be at least partially implemented inanother system, as a sub-system for example. In some embodiments, thecomputer system 110 and the computing environment 140 may begeographically distributed.

As persons skilled in the art of the present technology may appreciate,multiple variations as to how the computing environment 140 isimplemented may be envisioned without departing from the scope of thepresent technology.

Returning to the computer system 110 of FIGS. 4-6, the computer system110 or the processor 150 implements, a machine learned algorithm (MLA)for determining, by the MLA, the initial bend angle to be applied to theorthodontic appliance during bending in the gripped state for achievingthe desired bend angle in the free state.

The machine-learning algorithm, implemented by the computer system 100,may comprise, without being limitative, a non-linear regression, alinear regression, a logistic regression, a decision tree, a supportvector machine, a naïve bayes, K-nearest neighbors, K-means, randomforest, dimensionality reduction, neural network, gradient boostingand/or adaboost MLA.

In some embodiments, the MLA may be re-trained or further trained by thesystem 110 based on the data collected from the bending apparatus 120and/or the computer vision system 130, as well as on various parametersrelating to the archwire 10 such as composition, batch, manufacturer,diameter, width, thickness etc. In certain embodiments, the system 110is also arranged to execute a training phase of the MLA. In other words,an output from the computer vision system 130 is fed back into the MLAfor training or re-training.

Turning now to the bending apparatus 120, an embodiment of which isschematically illustrated in FIG. 7. As mentioned earlier, the bendingapparatus 120 is arranged to form the bend in the archwire 10 based oninstructions received from the computer system 110. The bendingapparatus 120 comprises a first gripping member 200 and a secondgripping member 210 configured to grip the archwire 10 along its lengthand move relative to each other whilst gripping the archwire 10 to formthe bend in the archwire 10. The first gripping member 200 is attachedto a robotic arm 220 having a plurality of axes of movement independentof the movement of the first gripping member 200. In this embodiment,the robotic arm 220 and the first gripping member 200 together providessix axes of movement. The bending apparatus 120 further comprises arobot control unit 230 for operatively controlling the movement of thefirst gripping member 200, the second gripping member 210 and therobotic arm 220. Bending of the archwire 10 is executed by relativemovement of the first gripping member 200 to the second gripping member210 whilst they are gripping the archwire 10. Each of the first andsecond gripping members 200, 210 have gripping surfaces (not shown) forgripping the archwire 10. The first and second gripping members 200, 210can move between an open state, which releases the archwire 10, and aclosed state, which grips the archwire 10. It will be appreciated thatthe archwire 10 can thus be transitioned from the gripped state to thefree state through manipulation of the first and second gripping members200, 210. The second gripping member 210 may be positionally fixed andimmobile other than its operation between the closed and open states.

The robot control unit 230 is operatively connected to the computersystem 110, such as to the processor 150, and can receive instructionsfrom the computer system 110 regarding the movement and operation of thefirst gripping member 200, the second gripping member 210, and/or therobotic arm 220 to form the bend in the archwire 10. Informationregarding the movement and operation of the first gripping member 200,the second gripping member 210, and/or the robotic arm 220 (e.g.co-ordinates) may be communicated between the robot control unit 230 andthe computer system 110. This information may include any one or more of(i) a desired bend angle in the archwire 10 in the free state, (ii) theinitial bend angle in the archwire 10 in the gripped state, (iii) anactual bend angle in the archwire 10 in the gripped state duringbending, and (iv) the resultant bend angle of the archwire 10 in thefree state. The actual bend angle in the archwire 10 in the grippedstate during bending may also be expressed as a change in angle or achange in deflection. The robot control unit 230 may be operativelyconnected to the computer system 110 as a wired or wireless connection.The computer system 110 may be at least partially incorporated in therobot control unit 230.

Also provided is a heating system for heating the archwire 10 whilstunder tension to form the pre-shape of the archwire 10. The heatingsystem comprises a heating control unit 250 operatively connected to apower supply 260, and heating elements 270 for heating the archwire 10through the first and second gripping members 200, 210. Heat may begenerated electrically by electrical current and resistance in thecircuit. Temperature sensor(s) are provided (not shown) for measuringthe temperature of the archwire 10 and/or the heating elements 270. Theheating control unit 250 is operatively connected to the computer system110 or the robot control unit 230 and can receive instructions regardingoperation of the heating of the archwire 10 from the computer system 110or the robot control unit 230. Information regarding the temperature ofthe archwire 10 and/or the heating elements 270 is provided to thecomputer system 110 or the robot control unit 230 for determining anoperation of the heating system. The operative connections between theheating control unit 250, the computer system 110 or the robot controlunit 230 are wired or wireless.

Other configurations of the bending apparatus 120 are possible andincluded within the scope of the present technology. For example, thebending apparatus 120 may take the form of one or a combination of anyof the bending apparatus as described in U.S. Pat. Nos. 6,612,143,6,732,558, 6,755,064, 6,860,132, 7,076,980, 7,283,891, US2008/0154644and US2010275668, the contents of which are incorporated herein byreference.

Turning now to FIG. 8 illustrating schematically certain embodiments ofthe computer vision system 130 of the system 100 of FIG. 5 forperforming a computer vision analysis and for monitoring the bending ofthe archwire 10. The computer vision system 130 comprises a camera 300for capturing images of the archwire 10 before, during and afterbending, and a vision control unit 310 operatively connected to thecomputer system 110 for performing a computer vision analysis of thecaptured images.

In certain embodiments, the camera 300 is a microscope capable ofcapturing video images, as image frames, at magnifications of about 50×to about 400×. The microscope may use optical magnification orelectronical (digital) magnification, which may also incorporate digitalstabilization. In certain embodiments, the microscope may also usecomposite camera 300 with combined optical and digital magnification.The frame rate of image capture is proportionally related to the bendingrate that can be used. In other words, the faster the frame rate, thefaster the bending can be performed. In certain embodiments, the frameacquisition rate is 70 to 300 frames per second. In certain embodiments,the camera 300 is arranged to digitally capture images at a high framerate, such as over 250 frames per second. In use, the camera 300 isarranged to focus on a segment of the archwire 10 which includes thebend or the area where the bend will be formed. Sequential image framesof this segment of the archwire 10 are captured during bending inreal-time. The vision control unit 310 processes the captured images toobtain an angle of the bend, also in real-time, and relays the output ofthe image processing to the computer system 100.

In certain embodiments, the computer vision system 130 includes abackground 320 that is positioned facing the camera 300 and behind thearchwire 10 for providing a contrast of the archwire 10 against thebackground for ease of image processing. In certain embodiments, thebackground 320 is a chroma key background or a light-absorbingbackground such as Vantablack™. In certain embodiments, the computervision system 130 includes a support surface on which the archwire 10 isplaced as well as the background 320. In certain embodiments, thesupport surface comprises a chroma key surface, and the backgroundcomprises a light-absorbing surface.

The vision control unit 310 comprises a processor (not shown) forcarrying out the computer vision analysis of the captured images tomonitor a bend angle, and one or more databases (not shown) for storingthe captured images and/or the processed images. The computer visionanalysis can be performed on each frame, or on sampled frames of thesequence of frames. During a monitoring phase, the angle of the bend ofthe archwire 10 is determined as a function of time. The bend angle maybe determined continuously during the bending process by continuousmonitoring of the bend angle during the bending process. The determinedangle may be an average based on closely-timed clusters of capturedimage frames of the imaged archwire segment.

The computer vision analysis comprises determining a contour of theimaged segment of the archwire 10. Based on the determined contour ofthe archwire 10, the computer vision analysis can derive one or moreelongate axes of the determined contour, the contour corresponding tothe imaged archwire 10 segment. For clarity, the imaged archwire 10segment may include a bend and two bend arms, each of the bend armshaving its own elongate axis. The angle of the bend can then bedetermined based on the elongate axes of the bend arms, in a manner thatwill be described later.

The contour of the imaged segment of the archwire 10 is determined usingimage processing or filtering steps. The image processing steps areselected from one or more of image pre-processing, image enhancement,image segmentation, image compression, image restoration, imagerepresentation, image recognition, image labelling, image formatconversion and the like. Image pre-processing includes scaling (e.g.sizing, cropping). Image enhancement includes functions such as focusadjustment, and image noise cancellation (e.g. erosion). The processoris also configured to change formats of the captured images, such as toa HSV format (Hue, Saturation, Value), which allows separation of colourcomponents from intensity for ease of certain image processing steps.

FIG. 9 depicts an example of a captured image frame of an imagedarchwire 10 segment using the embodiment of the computer vision system130 of FIG. 8. In this embodiment, the image processing steps includescaling and optionally sharpening of blurs, transformation of the imageto HSV format, determining a lightness channel of the image, and imagenoise cancelation.

In certain embodiments, the image noise cancellation comprises removingsmaller objects on the image using an erosion function. Relativelylarger objects on the image are ignored based on a determined area ofthe object relative to its length, based on the fact that the imagedarchwire 10 segments have an elongate form with larger areas. A furtherfiltering can be performed based on a roundness of the object, withrounder objects being ignored. A time-based approximation can then beperformed to reduce light noises (e.g. lens flares).

Referring back to determination of the angle of the bend from the imagedarchwire 10, the bent archwire 10 has two bend arms, one on either sideof the bend, and each having its own elongate axis. In certainembodiments, the angle of the bend comprises an angle between therespective elongate axes of the bend arms of the archwire 10. In otherembodiments, one of the bend arms of the archwire 10 may be used as areference axis for the bend angle determination. In this case, thereference axis may be established before the bending process isinitiated, in a set-up phase, by projecting a virtual reference axisonto the image of the archwire 10. During bending, the virtual referenceaxis is maintained in alignment with one of the bend arms of thearchwire 10 during the bending process. The angle of the bend is thendetermined as the angle between the virtual reference axis and theelongate axis of the other bend arm. In certain embodiments, thereference axis is the starting position 40 shown in FIG. 3. FIG. 10shows a filtered image of the archwire 10 segment on the left, and adetermined angle of the archwire 10 segment on the right.

The set-up phase may include a calibration step for normalizingvariations in orientation between the camera 300 and the archwire 10segment being imaged (this orientation may differ between differentmonitoring/bending tests). The calibration step comprises detecting anangle between a line of vision of the camera 300 and the archwire 10segment being imaged, and normalizing this angle with a reference angle.

The bend angle of the archwire 10 in the free state is measured in asimilar manner as described above. Specifically, once the bendingapparatus 120 has released one of the gripping members 200, 210, imagesof the segment of the archwire 10 including the bend are captured, andprocessed as described above to determine the free state bend angle.

In other embodiments, the computer vision system 130 has a differentconfiguration than the one described in relation to FIGS. 8-10. Forexample, the camera 300, or the image processing steps may differ. Incertain embodiments, instead of a computer vision system 130, any otherdevice or system for continuously monitoring the bending of the archwire10 may be provided, such as strain gauges.

In some embodiments, the computer system 110 is connectable to thebending apparatus 120, and/or the computer vision system 130 via acommunication network. In some embodiments, the communication network isthe Internet and/or an Intranet. Multiple embodiments of thecommunication network may be envisioned and will become apparent to theperson skilled in the art of the present technology.

In some embodiments, the computer system 110 is connectable to thebending apparatus 120, and/or the computer vision system 130 via theprocessor 150. In some other embodiments, the computer system 110 may bedirectly connected to the bending apparatus 120, and/or the computervision system 130. In some alternative embodiments, the computer system110 or the computing environment 140 is implemented, at least partially,on the bending apparatus 120, and/or the computer vision system 130. Inyet some alternative embodiments, the computer system 110 may be hosted,at least partially, on a server. In some alternative embodiments, thesystem may be partially or totally virtualized through a cloudarchitecture.

With reference now to FIG. 11, in certain embodiments the computersystem 110 is configured to execute a method 400 for forming the desiredbend angle in the archwire 10. The method 400 will now be described infurther detail below.

STEP 402: Obtaining an Indication of the Desired Bend Angle in theOrthodontic Appliance

The method begins at step 402 with the computer system 110 obtaining anindication of the desired bend angle in the orthodontic appliance (e.g.the archwire 10). In the embodiment of FIG. 2, the desired bend angle ofbend A is the bend angle θ_(A) in the position 50. The desired bendangle is when the archwire is in the free state.

In certain embodiments, the desired bend angle is based on a treatmentplan determined by a clinician, such as an orthodontist or a dentist.The desired bend angle can be determined by any method such as a manualdetermination or a computer model-based determination.

In certain embodiments, the obtaining the indication of the desired bendangle in the orthodontic appliance comprises receiving the indicationfrom an operator of the computer system, such as through a userinterface.

In other embodiments, the obtaining the indication of the desired bendangle in the orthodontic appliance comprises calculating, by thecomputer system 110 or another computer system, the desired bend angle.

For archwires 10 having a plurality of bends, such as the archwire 10 ofFIGS. 1-3, the desired bend angle can be relative to a position of anadjacent portion of the archwire 10 as illustrated in FIG. 2.Alternatively, each desired bend angle can be determined based on abaseline starting position.

STEP 404: Determining, by the MLA, an Initial Bend Angle to be Appliedto the Orthodontic Appliance During Bending in a Gripped State of theOrthodontic Appliance for Achieving the Desired Bend Angle in theOrthodontic Appliance When the Orthodontic Appliance is in a Free State

At step 404, the computer system 110 causes execution of the MLA todetermine the initial bend angle to be applied to the orthodonticappliance, e.g. the archwire 10, in the gripped state, so that thedesired bend angle in the free state can be achieved. In the example ofFIG. 3, the initial bend angle is an over-bend angle θ_(AOB) to takeinto account an elastic property of the archwire 10 which causes it tospring back to the desired bend angle in the free state.

STEP 406: Causing the Bending Apparatus to Form a Bend Having theInitial Bend Angle in the Orthodontic Appliance, by Bending theOrthodontic Appliance in the Gripped State

In certain embodiments, the bend is formed by the computer system 100sending instructions to the bending apparatus 120 of FIG. 7, forexample. The bending apparatus 120, on receiving instructions from thecomputer system 110, grips the archwire 10 using the first and secondgripping members 200, 210, and causes the archwire 10 to bend byapplying a relative movement of the first and second gripping members200, 210.

STEP 408: Monitoring the Bending of the Orthodontic Appliance in theGripped State Through a Computer Vision Analysis

In certain embodiments, the computer vision analysis is performed by thecomputer vision system 130.

Monitoring of the bending of the orthodontic appliance may comprise:capturing a sequence of images of the bend of the archwire 10 as it isbeing formed during the bending; filtering or processing the images todetermine a contour of the orthodontic appliance; determining twoelongate (longitudinal) axes of the orthodontic appliance from thecontour; and determining an angle between the two longitudinal axes ofthe orthodontic appliance.

In certain embodiments, the filtering of the images comprises one ormore of image scaling, adjusting focus, and cancelling image noise. Thefiltering may also comprise converting the captured images to HSV imageformat.

In certain embodiments, the monitoring of the bending of the orthodonticappliance comprises determining an angle of the bend being formedrelative to a starting position or reference axis. In certainembodiments, the starting position comprises projecting a virtual axisonto the image of the wire before the bending process is initiated, andaligning the virtual axis with the elongate axis of the archwire 10before causing the bending apparatus to form the bend.

In certain embodiments, the monitoring the bending of the orthodonticappliance in the gripped state through the computer vision analysiscomprises continuously monitoring the bending of the orthodonticappliance in the gripped state throughout an entire bending process. Themonitoring can be in real-time.

STEP 410: In Response to the Computer Vision Analysis Rendering anIndication That the Initial Bend Angle in the Orthodontic Appliance inthe Gripped State has Been Reached, Causing the Bending Apparatus toRelease at Least a Portion of the Orthodontic Appliance so that theOrthodontic Appliance is in the Free State

In certain embodiments, a feedback loop based on the computer visionanalysis provides an indication to the computer system 110 that theinitial bend angle has been reached. The computer system 110 can thenprovide instructions to the bending apparatus 120 to stop the bendingoperation, and to release the archwire 10 so that a measurement of aresultant bend angle in the free state can be performed.

STEP 412: Measuring a Resultant Angle of the Bend Through the ComputerVision Analysis, when the Orthodontic Appliance is in the Free State

In certain embodiments, the resultant angle of the bend is performed bycapturing at least one image of the formed bend; filtering the image todetermine a contour of the orthodontic appliance; determining twoelongate (longitudinal) axes of the orthodontic appliance from thecontour; and determining an angle between the two longitudinal axes ofthe orthodontic appliance.

In other embodiments, only one longitudinal axis is determined andcompared to the starting position with which a segment of the archwirewhich did not move during bending is aligned.

In certain embodiments, the filtering of the image comprises one or moreof image scaling, adjusting focus, and cancelling image noise. Thefiltering can further comprise converting the captured images to HSVformat.

STEP 414: Selectively Executing: in Response to the Resultant AngleBeing Within a Predefined Tolerance Level of the Desired Bend Angle,Determining that the Orthodontic Appliance has Reached the Desired BendAngle; and in Response to the Resultant Angle Being Outside thePredefined Tolerance Level of the Desired Bend Angle, IterativelyApplying an Adjusted Bend Angle to the Orthodontic Appliance in theGripped State Until the Desired Bend Angle is Achieved as Determined bythe Computer Vision Analysis in the Free State.

In certain embodiments, if it is determined that the desired bend anglehas been achieved according to a predefined tolerance level, the methodends at step 414.

In certain embodiments, if it is determined that the resultant angle isoutside of the predefined tolerance level, the method continues byapplying an adjusted bend angle to the archwire 10. The adjusted bendangle may be determined by the MLA and have the effect of reducing orincreasing the resultant angle depending on whether the resultant anglewas above or below the desired bend angle.

As before, the bending of the archwire 10 in the gripped state throughthe computer vision analysis is monitored. When the computer visionanalysis renders an indication that the adjusted bend angle in thegripped state has been reached, the computer system 100 causes thebending apparatus 120 to release at least a portion of the archwire 10so that the archwire 10 is in the free state and the resultant angle inthe free state can be measured. The computer vision analysis determinesthe resultant angle in the free state. The method ends if the resultantangle in the free state is within the predefined tolerance level of thedesired bend angle. If not, the method continues by applying furtheriteration(s) of a further adjusted bend angle to the archwire 10 untilthe desired bend angle in the free state of the archwire 10 is achievedas determined by computer vision analysis.

In a further step, the method 400 may comprise feeding the adjusted bendangle or the further adjusted bend angle, together with their respectiveresultant angles in the free state to the MLA to be used for furtherretraining of the MLA.

In certain embodiments, the method 400 further comprises the computersystem 110 executing a training process for the training of the MLA. Thetraining process may occur before the method steps 402-414 listed above.The training process may include providing a feedback loop based on acomputer vision analysis.

In certain embodiments, the training process comprises providing atleast one training set, the training set including an indication of aproperty of the archwire 10 and a target value representative of adesired bend. The property of the archwire 10 may include at least oneof: an elasticity property of a material from which the archwire 10 isformed, a thickness of the archwire 10, a diameter of the archwire 10, acomposition of the archwire 10, and a manufacturing process of thearchwire 10.

In certain embodiments, the training process further comprises:executing a test bending to bend a test archwire 10 to the desired bend;calculating a variance parameter between an actual bend and the desiredbend; and feeding back the variance parameter to the MLA for furtherretraining of the MLA.

In certain embodiments, the training process further comprisesiteratively executing the training process until the variance parameteris within a pre-determined acceptable error threshold.

According to another aspect of the present technology, there is alsoprovided a method 500 for training a Machine Learning Algorithm (MLA),the MLA for determining, in use, a bend angle to be applied to anorthodontic appliance during bending in a gripped state for achieving adesired bend angle in the orthodontic appliance when in a free state.The method 500 is implemented by the computer system 110, such as theprocessor 150, the computer system 110 being operatively coupled to thebending apparatus 120. The method 500 commences at step 502.

Step 502: Obtaining an Indication of the Desired Bend Angle in theOrthodontic Appliance

The method begins at step 502 with the computer system 110 obtaining anindication of the desired bend angle in the orthodontic appliance (e.g.the archwire 10). In the embodiment of FIG. 2, the desired bend angle ofbend A is the bend angle θ_(A) in the position 50. The desired bendangle is when the archwire 10 is in the free state.

In certain embodiments, the desired bend angle is based on a treatmentplan determined by a clinician, such as an orthodontist or a dentist.The desired bend angle can be determined by any method such as a manualdetermination or a computer model-based determination.

In certain embodiments, the obtaining the indication of the desired bendangle in the orthodontic appliance comprises receiving the indicationfrom an operator of the computer system, such as through a userinterface.

In other embodiments, the obtaining the indication of the desired bendangle in the orthodontic appliance comprises calculating, by thecomputer system 110 or another computer system, the desired bend angle.

For archwires 10 having a plurality of bends, such as the archwire 10 ofFIGS. 1-3, the desired bend angle can be relative to a position of anadjacent portion of the archwire 10 as illustrated in FIG. 2.Alternatively, each desired bend angle can be determined based on abaseline starting position.

STEP 504: Causing the Bending Apparatus to Form a Bend Having theInitial Bend Angle in the Orthodontic Appliance, by Bending theOrthodontic Appliance in the Gripped State

In certain embodiments, the bend is formed by the computer system 100sending instructions to the bending apparatus 120 of FIG. 7, forexample. The bending apparatus 120, on receiving instructions from thecomputer system 110, grips the archwire 10 using the first and secondgripping members 200, 210, and causes the archwire 10 to bend byapplying a relative movement of the first and second gripping members200, 210.

STEP 506: In Response to the Computer Vision Analysis Rendering anIndication that the Initial Bend Angle in the Orthodontic Appliance inthe Gripped State has Been Reached, Causing the Bending Apparatus toRelease at Least a Portion of the Orthodontic Appliance so that theOrthodontic Appliance is in the Free State

In certain embodiments, a feedback loop based on the computer visionanalysis provides an indication to the computer system 110 that theinitial bend angle has been reached. The computer system 110 can thenprovide instructions to the bending apparatus 120 to stop the bendingoperation, and to release the archwire 10 so that a measurement of aresultant bend angle in the free state can be performed.

STEP 508: Obtaining a Measure of a Resultant Angle of the Bend Throughthe Computer Vision Analysis, When the Orthodontic Appliance is in theFree State

In certain embodiments, the obtaining the measure of the resultant angleof the bend, when the orthodontic appliance is in the free state,comprises applying an optical feedback analysis.

The optical feedback analysis comprises, in certain embodiments,monitoring the bending of the orthodontic appliance in the gripped statethrough a computer vision analysis to determine when the initial bendangle in the orthodontic appliance in the gripped state has beenreached; and measuring a resultant angle of the bend through thecomputer vision analysis, when the orthodontic appliance is in the freestate. The optical feedback analysis further comprises the computersystem 110 selectively executing: in response to the resultant anglebeing within a predefined tolerance level of the desired bend angle,determining that the orthodontic appliance has reached the desired bendangle; and in response to the resultant angle being outside thepredefined tolerance level of the desired bend angle, iterativelyapplying an adjusted bend angle to the orthodontic appliance in thegripped state until the desired bend angle is achieved as determined bythe computer vision analysis in the free state.

In certain embodiments, the resultant angle of the bend is performed bycapturing at least one image of the formed bend; filtering the image todetermine a contour of the orthodontic appliance; determining twolongitudinal axes of the orthodontic appliance from the contour; anddetermining an angle between the two longitudinal axes of theorthodontic appliance.

In other embodiments, only one longitudinal axis is determined andcompared to a virtual starting position axis with which a segment of thearchwire which did not move during bending is aligned.

In certain embodiments, the filtering of the image comprises one or moreof image scaling, adjusting focus, and cancelling image noise. Thefiltering can further comprise converting the captured images to HSVformat.

STEP 510: Generating a Training Set for Training the MLA

In certain embodiments, the training set includes an indication of aproperty of the archwire 10 and a target value representative of adesired bend.

The property of the archwire 10 may include at least one of: anelasticity property of a material from which the archwire 10 is formed,a thickness of the archwire 10, a diameter of the archwire 10, acomposition of the archwire 10, and a manufacturing method of thearchwire 10. The target value may comprise the initial bend angle.

The training set is configured to train the MLA to predict the initialbend angle based on the desired bend angle and the property of thearchwire 10.

In certain embodiments, the method 500 further comprises calculating adifference parameter between the resultant angle of the bend and theinitial bend angle and feeding the difference parameter as an indicationof the prediction error.

In certain embodiments, the method further comprises iterativelyrepeating the method for training until the prediction error is within apre-determined threshold.

It should be expressly understood that not all technical effectsmentioned herein need to be enjoyed in each and every embodiment of thepresent technology.

Modifications and improvements to the above-described implementations ofthe present technology may become apparent to those skilled in the art.The foregoing description is intended to be exemplary rather thanlimiting. The scope of the present technology is therefore intended tobe limited solely by the scope of the appended claims.

The invention claimed is:
 1. A method for forming a desired bend anglein an orthodontic appliance, the method being implemented by a processorof a computer system, the computer system operatively coupled to abending apparatus, the method comprising: monitoring bending of theorthodontic appliance in a gripped state through a computer visionanalysis, the monitoring being a continuous monitoring of the bending ofthe orthodontic appliance in the gripped state throughout an entirebending process; in response to the computer vision analysis renderingan indication that an initial bend angle in the orthodontic appliance ina gripped state having been reached, causing the bending apparatus torelease at least a portion of the orthodontic appliance so that theorthodontic appliance is in a free state, the initial bend angle havingbeen determined by a Machine Learning Algorithm (MLA); measuring aresultant angle of the bend through the computer vision analysis, whenthe orthodontic appliance is in the free state; in response to theresultant angle being within a predefined tolerance level of the desiredbend angle, determining that the orthodontic appliance has reached thedesired bend angle; wherein the monitoring of the bending of theorthodontic appliance comprises: capturing a sequence of images of thebend as it is being formed during the bending; filtering the images todetermine a contour of the orthodontic appliance, determining at leastone elongate axis of the orthodontic appliance from the contour; anddetermining an angle between the at least one elongate axis of theorthodontic appliance and a reference axis, or between two elongate axesof the orthodontic appliance.
 2. The method of claim 1, furthercomprising: in response to the resultant angle being outside thepredefined tolerance level of the desired bend angle, iterativelyapplying an adjusted bend angle to the orthodontic appliance in thegripped state until the desired bend angle is achieved as determined bythe computer vision analysis in the free state.
 3. The method of claim1, wherein the computer system executes the MLA for determining theinitial bend angle to be applied to the orthodontic appliance duringbending in the gripped state of the orthodontic appliance for achievingthe desired bend angle in the orthodontic appliance when the orthodonticappliance is in the free state.
 4. The method of claim 1, wherein theobtaining the indication of the desired bend angle in the orthodonticappliance comprises receiving the indication from an operator of thecomputer system.
 5. The method of claim 1, wherein the obtaining theindication of the desired bend angle in the orthodontic appliancecomprises calculating, by the computer system, the desired bend angle.6. The method of claim 1, wherein the method further comprises, prior tothe obtaining the indication of the desired bend angle: executing atraining process for the MLA.
 7. The method of claim 6, wherein thetraining process includes providing a feedback loop based on thecomputer vision analysis.
 8. The method of claim 6, wherein the trainingprocess comprises providing at least one training set, the training setincluding an indication of a property of the orthodontic appliance and atarget value representative of a desired bend; the property of theorthodontic appliance including at least one of: an elasticity propertyof a material from which the orthodontic appliance is formed, athickness of the orthodontic appliance, a diameter of the orthodonticappliance, a composition of the material from which the orthodonticappliance is formed, and a manufacturing process of the orthodonticappliance.
 9. The method of claim 8, wherein the training processfurther comprises: executing a test bending to bend a test orthodonticappliance to the desired bend; calculating a variance parameter betweenan actual bend and the desired bend; feeding back the variance parameterto the MLA for further retraining of the MLA.
 10. The method of claim 9,further comprising iteratively executing the training process until thevariance parameter is within a pre-determined acceptable errorthreshold.
 11. The method of claim 1, in response to the resultant anglebeing outside the predefined tolerance level of the desired bend angle,iteratively applying an adjusted bend angle to the orthodontic appliancein the gripped state until the desired bend angle is achieved asdetermined by the computer vision analysis in the free state, the methodfurther comprising feeding the adjusted bend angle to the MLA to be usedfor further retraining of the MLA.
 12. The method of claim 1, whereinthe reference axis is determined by projecting a virtual axis onto, andaligned with, the image of the orthodontic appliance before causing thebending apparatus to form the bend in the orthodontic appliance.
 13. Themethod of claim 1, wherein the filtering comprising one or more of imagescaling, adjusting focus, and cancelling image noise, the filteredimages being of HSV image format.
 14. A system for forming a desiredbend angle in an orthodontic appliance, the system comprising: a bendingapparatus operatively coupled to a computer system; the computer systemhaving a processor arranged to execute a method, the method comprising:monitoring bending of the orthodontic appliance in a gripped statethrough a computer vision analysis, the monitoring being a continuousmonitoring of the bending of the orthodontic appliance in the grippedstate throughout an entire bending process; in response to the computervision analysis rendering an indication that an initial bend angle inthe orthodontic appliance in a gripped state having been reached,causing the bending apparatus to release at least a portion of theorthodontic appliance so that the orthodontic appliance is in a freestate, the initial bend angle having been determined by a MachineLearning Algorithm (MLA); measuring a resultant angle of the bendthrough the computer vision analysis, when the orthodontic appliance isin the free state; and in response to the resultant angle being within apredefined tolerance level of the desired bend angle, determining thatthe orthodontic appliance has reached the desired bend angle; whereinthe monitoring of the bending of the orthodontic appliance comprises:capturing a sequence of images of the bend as it is being formed duringthe bending; filtering the images to determine a contour of theorthodontic appliance, determining at least one elongate axis of theorthodontic appliance from the contour; and determining an angle betweenthe at least one elongate axis of the orthodontic appliance and areference axis, or between two elongate axes of the orthodonticappliance.
 15. The system of claim 14, further comprising a computervision system arranged to perform at least a portion of the computervision analysis, the computer system and the computer vision systembeing operatively connected thereto.
 16. A method for monitoring aformation of a bend in an orthodontic appliance, the method beingimplemented by a processor of a computer system operatively connected toa computer vision system, the method comprising: obtaining a sequence ofimage frames of the orthodontic appliance during a bending process, theorthodontic appliance having a first bend arm and a second bend arm; forat least one of the image frames of the sequence of image frames:applying image processing steps to objects in the image frames to detectat least a portion of the first bend arm and at least a portion of thesecond bend arm; deriving one or more of: an elongate axis of the firstbend arm based on the detected at least portion of the first bend arm,and an elongate axis of the second bend arm based on the detected atleast portion of the second bend arm; determining a bend angle of theorthodontic appliance based on: the elongate axis of the first bend armand the elongate axis of the second bend arm, or the elongate axis ofthe first bend arm or the second bend arm, and a reference axis; whereinthe reference axis is determined by projecting a virtual axis onto, andaligned with, the image of the orthodontic appliance before causing abending apparatus to form the bend in the orthodontic appliance.
 17. Themethod of claim 16, wherein the bend angle of the orthodontic applianceis monitored continuously during the bending process.
 18. The method ofclaim 16, further comprising maintaining the alignment of the virtualaxis on an image of at least a portion of the orthodontic applianceduring the bending process.